Subject: [merged] revert-mm-vmalloc-interchage-the-implementation-of-vmalloc_to_pfnpage.patch removed from -mm tree
To: av1474@xxxxxxxx,murzin.v@xxxxxxxxx,nasa4836@xxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 28 Jan 2014 11:09:07 -0800
The patch titled
Subject: Revert "mm/vmalloc: interchage the implementation of vmalloc_to_{pfn,page}"
has been removed from the -mm tree. Its filename was
revert-mm-vmalloc-interchage-the-implementation-of-vmalloc_to_pfnpage.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: malc <av1474@xxxxxxxx>
Subject: Revert "mm/vmalloc: interchage the implementation of vmalloc_to_{pfn,page}"
Revert ece86e222db48d04bda, which was intended as a small performance
improvement.
Despite the claim that the patch doesn't introduce any functional changes
in fact it does.
The "no page" path behaves different now. Originally, vmalloc_to_page
might return NULL under some conditions, with new implementation it
returns pfn_to_page(0) which is not the same as NULL.
Simple test shows the difference.
test.c
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
int __init myi(void)
{
struct page *p;
void *v;
v = vmalloc(PAGE_SIZE);
/* trigger the "no page" path in vmalloc_to_page*/
vfree(v);
p = vmalloc_to_page(v);
pr_err("expected val = NULL, returned val = %p", p);
return -EBUSY;
}
void __exit mye(void)
{
}
module_init(myi)
module_exit(mye)
Before interchange:
expected val = NULL, returned val = (null)
After interchange:
expected val = NULL, returned val = c7ebe000
Signed-off-by: Vladimir Murzin <murzin.v@xxxxxxxxx>
Cc: Jianyu Zhan <nasa4836@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff -puN mm/vmalloc.c~revert-mm-vmalloc-interchage-the-implementation-of-vmalloc_to_pfnpage mm/vmalloc.c
--- a/mm/vmalloc.c~revert-mm-vmalloc-interchage-the-implementation-of-vmalloc_to_pfnpage
+++ a/mm/vmalloc.c
@@ -220,12 +220,12 @@ int is_vmalloc_or_module_addr(const void
}
/*
- * Walk a vmap address to the physical pfn it maps to.
+ * Walk a vmap address to the struct page it maps.
*/
-unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
+struct page *vmalloc_to_page(const void *vmalloc_addr)
{
unsigned long addr = (unsigned long) vmalloc_addr;
- unsigned long pfn = 0;
+ struct page *page = NULL;
pgd_t *pgd = pgd_offset_k(addr);
/*
@@ -244,23 +244,23 @@ unsigned long vmalloc_to_pfn(const void
ptep = pte_offset_map(pmd, addr);
pte = *ptep;
if (pte_present(pte))
- pfn = pte_pfn(pte);
+ page = pte_page(pte);
pte_unmap(ptep);
}
}
}
- return pfn;
+ return page;
}
-EXPORT_SYMBOL(vmalloc_to_pfn);
+EXPORT_SYMBOL(vmalloc_to_page);
/*
- * Map a vmalloc()-space virtual address to the struct page.
+ * Map a vmalloc()-space virtual address to the physical page frame number.
*/
-struct page *vmalloc_to_page(const void *vmalloc_addr)
+unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
{
- return pfn_to_page(vmalloc_to_pfn(vmalloc_addr));
+ return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}
-EXPORT_SYMBOL(vmalloc_to_page);
+EXPORT_SYMBOL(vmalloc_to_pfn);
/*** Global kva allocator ***/
_
Patches currently in -mm which might be from av1474@xxxxxxxx are
origin.patch
arm-move-arm_dma_limit-to-setup_dma_zone.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
